Manage external locations

This article describes how to list, view, update, grant permissions on, enable file events for, and delete external locations.

To see the properties of an external location, including permissions and workspace access, you can use Catalog Explorer or a SQL command.

1. In the sidebar, click Catalog.

2. On the Quick access page, click the External data > button to go to the External Locations tab.

3. Click the name of an external location to view its properties.

Run the following command in a notebook or the Databricks SQL editor. Replace <location-name> with the name of the external location.

DESCRIBE EXTERNAL LOCATION <location-name>;

To show grants on an external location, use a command like the following. You can optionally filter the results to show only the grants for the specified principal.

SHOW GRANTS [<principal>] ON EXTERNAL LOCATION <location-name>;

Replace the placeholder values:

• <location-name>: The name of the external location that authorizes reading from and writing to the storage container path in your cloud tenant.
• <principal>: The email address of an account-level user or the name of an account-level group.

This section describes how to grant and revoke permissions on an external location using Catalog Explorer and SQL commands in a notebook or SQL query. For information about using the Databricks CLI or Terraform instead, see the Databricks Terraform documentation and What is the Databricks CLI?.

You can grant the following permissions on an external location:

• CREATE EXTERNAL TABLE
• CREATE EXTERNAL VOLUME
• CREATE MANAGED STORAGE

Permissions required: The CREATE EXTERNAL LOCATION privilege on both the metastore and the storage credential referenced in the external location or the MANAGE privilege on the external location. Metastore admins have CREATE EXTERNAL LOCATION on the metastore by default.

To grant permission to use an external location:

1. In the sidebar, click Catalog.

2. On the Quick access page, click the External data > button to go to the External Locations tab.

3. Click the name of an external location to open its properties.

4. Click Permissions.

5. To grant permission to users or groups, select each identity, then click Grant.

6. To revoke permissions from users or groups, select each identity, then click Revoke.

Run the following SQL command in a notebook or SQL query editor. This example grants the ability to create an external table that references the external location:

GRANT CREATE EXTERNAL TABLE ON EXTERNAL LOCATION <location-name> TO <principal>;

Replace the placeholder values:

• <location-name>: The name of the external location that authorizes reading from and writing to the storage container path in your cloud tenant.
• <principal>: The email address of an account-level user or the name of an account-level group.

An external location's creator is its initial owner. To change the owner to a different account-level user or group, run the following command in a notebook or the Databricks SQL editor or use Catalog Explorer.

Permissions required: External location owner or a user with the MANAGE privilege.

Replace the placeholder values:

• <location-name>: The name of the credential.
• <principal>: The email address of an account-level user or the name of an account-level group.

ALTER EXTERNAL LOCATION <location-name> OWNER TO <principal>

If you want users to have read-only access to an external location, you can use Catalog Explorer to mark the external location as read-only.

Making external locations read-only:

• Prevents users from writing to files in those external locations, regardless of any write permissions granted by the Azure managed identity that underlies the storage credential, and regardless of the Unity Catalog permissions granted on that external location.
• Prevents users from creating managed tables or volumes in those external locations.
• Enables the system to validate the external location properly at creation time.

You can mark external locations as read-only when you create them.

You can also use Catalog Explorer to change read-only status after creating an external location:

1. In the sidebar, click Catalog.

2. On the Quick access page, click the External data > button to go to the External Locations tab.

3. Select the external location, click the menu next to the Test connection button, and select Edit.

4. On the edit dialog, click Advanced Options and select the Limit to read-only use option.

5. Click Update.

If you want to ingest change notifications that are pushed by the cloud provider, enabling managed file events for the external location has the following advantages:

• Makes it easier to set up file notifications for Auto Loader. Specifically, it enables incremental file discovery with notification-like performance in Auto Loader by setting cloudFiles.useManagedFileEvents to true. See What is Auto Loader file notification mode?.
• Improves the efficiency and capacity of file arrival triggers for jobs. See Trigger jobs when new files arrive.

If you want Azure Databricks to configure storage queues in Azure Data Lake Storage on your behalf, your external location must reference a storage credential that gives adequate permissions to do so. See the next step for instructions.

If you want to create your own storage queues in Azure Data Lake Storage, the identity represented by the storage credential must have the following permission on those storage queues:

Storage Queue Data Contributor

Before you can enable file events for the external location securable object, you must ensure that your Azure Data Lake Storage account is configured to give Azure Databricks access to the file events that it emits. If you want Azure Databricks to configure file events in Azure Data Lake Storage for you, you must also ensure that Azure Databricks has the proper access.

Assigning this access is an optional step when you configure managed identities that can access storage locations using Azure Databricks and Unity Catalog. To confirm that the managed identity that gives access to the external location is configured properly:

1. Get the Azure managed identity ID.

   1. In the sidebar, click Catalog.

   2. On the Quick access page, click the External data > button to go to the External Locations tab.

   3. Select the external location.

   4. On the Overview tab, click the Credential name.

   5. On the storage credential Overview tab, copy the Connector Id or User Assigned Managed Identity Id.

      You will use this in the next step.

2. Log into your Azure Data Lake Storage account.

3. Go to Access Control (IAM) and click the Check access button.

4. In Managed identity, select either User-assigned managed identity or Access Connector for Azure Databricks, depending on the managed identity type.

5. Search for the managed identity that you copied in step 1.

6. Confirm that the managed identity has the following roles:

   • Storage Blob Data Contributor
   • EventGrid EventSubscription Contributor
   • Storage Queue Data Contributor: Required only if you want Azure Databricks to create a subscription and events in Azure Data Lake Storage for you. If you do not enable this role, you must create the Azure storage queue yourself).

7. If any of these roles is missing, go to the Eligible assignments tab and add them.

For more information about assigning these roles, see Step 3: Grant the managed identity access to file events and Step 4: Grant Azure Databricks access to configure file events on your behalf.

To enable file events:

1. In the sidebar, click Catalog.

2. On the Quick access page, click the External data > button to go to the External Locations tab.

3. Select the external location.

4. Click the kebab menu next to the Test connection button, and select Edit.

5. On the edit dialog, click Advanced Options.

6. Select Enable file events.

7. Select the File event type:

   Automatic: (Recommended) select this if you want Azure Databricks to set up subscriptions and events for you.

   Provided: Select this if you have already configured an Azure storage queue yourself.

8. If you selected the Provided file event type, enter the Queue URL of the existing storage queue: https://<storage account>.queue.core.chinacloudapi.cn/<queue>.

9. Click Update.

10. Wait a few seconds and click Test connection on the main external location edit page to confirm that file events have been enabled successfully.

Managed file events have the following limitations:

• Event throughput is limited to 2000 files ingested per second.

• With managed file events, you cannot tag cloud resources using the resourceTags option. Instead, you can tag resources using the cloud console after the Auto Loader service creates your queue and subscription resources.

• You can't set up file notifications for the Unity Catalog metastore root storage location.

  Specifically, you can't set up file notifications using file events on storage locations that have no external location object defined in Unity Catalog. Older implementations of Unity Catalog include a metastore root storage location that is not associated with an external location. In newer implementations, specifically those on workspaces that were enabled for Unity Catalog automatically, the metastore-level storage does have an external location defined for it, and managed file events are supported on that storage location. If you're as confused as I sound, see Automatic enablement of Unity Catalog.

• Azure Blob Storage is not supported.

An external location's owner or a user with the MANAGE privilege can rename, change the URI, and change the storage credential of the external location.

To rename an external location, do the following:

Run the following command in a notebook or the Databricks SQL editor. Replace the placeholder values:

• <location-name>: The name of the location.
• <new-location-name>: A new name for the location.

ALTER EXTERNAL LOCATION <location-name> RENAME TO <new-location-name>;

To change the URI that an external location points to in your cloud tenant, do the following:

Run the following command in a notebook or the Databricks SQL editor. Replace the placeholder values:

• <location-name>: The name of the external location.
• <url>: The new storage URL the location should authorize access to in your cloud tenant.

ALTER EXTERNAL LOCATION location_name SET URL '<url>' [FORCE];

The FORCE option changes the URL even if external tables depend upon the external location.

To change the storage credential that an external location uses, do the following:

Run the following command in a notebook or the Databricks SQL editor. Replace the placeholder values:

• <location-name>: The name of the external location.
• <credential-name>: The name of the storage credential that grants access to the location's URL in your cloud tenant.

ALTER EXTERNAL LOCATION <location-name> SET STORAGE CREDENTIAL <credential-name>;

To delete (drop) an external location you must be its owner or have the MANAGE privilege on the external location. To delete an external location, do the following:

Run the following command in a notebook or the Databricks SQL editor. Items in brackets are optional. Replace <location-name> with the name of the external location.

DROP EXTERNAL LOCATION [IF EXISTS] <location-name>;